A method for providing under bump metallization on a substrate. Trenches are formed in the substrate, and a layer of first electrically conductive material is formed over the substrate. The layer of the first electrically conductive material substantially fills the trenches and substantially covers the substrate between the trenches in a contiguous sheet. The layer of the first electrically conductive material is thinned to an end point where the layer of the first electrically conductive material is substantially reduced in thickness, but still forms the contiguous sheet between the trenches. A layer of photoresist is applied over the layer of the first electrically conductive material to define openings. A second electrically conductive material is deposited into the openings. The photoresist layer is removed, and the layer of the first electrically conductive material in the contiguous sheet between the trenches is removed to isolate the first electrically conductive material in the trenches. Because the layer of the first electrically conductive material is not completely removed in the areas between the trenches, the first electrically conductive material may be used as an electrode for the electroplate deposition of the second electrically conductive material. Thus, the under bump metallization can be produced in a more economical manner. If the layer of the first electrically conductive material were to be thinned to the point where the first electrically conductive material was only left in the trenches, then it would not be feasible to used the layer of the first electrically conductive material as an electrode, and thus it would further not be feasible to electroplate the second electrically conductive material.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for providing under bump metallization on a substrate, the method comprising the steps of: forming trenches in the substrate, forming a layer of a first electrically conductive material over the substrate, the layer of the first electrically conductive material completely filling the trenches and substantially covering the substrate between the trenches in a contiguous sheet, thinning the layer of the first electrically conductive material to an end point where the layer of the first electrically conductive material is substantially reduced in thickness but still forms the contiguous sheet between the trenches, applying a photoresist layer over the layer of the first electrically conductive material to define openings, depositing a second electrically conductive material into the openings, removing the photoresist layer, and removing the layer of the first electrically conductive material in the contiguous sheet between the trenches to isolate the first electrically conductive material in the trenches.
2. The method of claim 1 , further comprising the step of forming a barrier layer over the substrate prior to the step of forming the layer of the first electrically conductive material over the substrate.
3. The method of claim 2 , wherein the barrier layer comprises a composite layer of tantalum and tantalum nitride.
4. The method of claim 1 , further comprising the steps of forming a barrier layer over the substrate and forming a seed layer over the barrier layer prior to the step of forming the layer of the first electrically conductive material over the substrate.
5. The method of claim 4 , wherein the barrier layer comprises a composite layer of tantalum and tantalum nitride.
6. The method of claim 4 , wherein the seed layer comprises the first electrically conductive material.
7. The method of claim 1 wherein the first electrically conductive material comprises copper.
8. The method of claim 1 wherein the second electrically conductive material comprises nickel.
9. The method of claim 1 further comprising the step of depositing a third electrically conductive material in the openings after the step of depositing a second electrically conductive material in the openings.
10. The method of claim 9 wherein the third electrically conductive material comprises gold.
11. The method of claim 9 wherein the third electrically conductive material comprises solder.
12. The method of claim 1 wherein the step of forming the layer of the first electrically conductive material over the substrate comprises electroplating the layer of the first electrically conductive material.
13. The method of claim 1 wherein the step of thinning the layer of the first electrically conductive material comprises chemical mechanically polishing the layer of the first electrically conductive material.
14. The method of claim 1 wherein the step of depositing a second electrically conductive material into the openings comprises electroplating the second electrically conductive material.
15. The method of claim 1 , further comprising the steps of: depositing a layer of electrically nonconductive material over the substrate, and etching the layer of electrically nonconductive material to expose the second electrically conductive material overlying the trenches.
16. A method for providing under bump metallization on a substrate, the method comprising the steps of: forming trenches in the substrate, forming a barrier layer over the substrate, forming a seed layer of a first electrically conductive material over the barrier layer, electroplating a conduction layer of the first electrically conductive material over the seed layer, the layer of the first electrically conductive material completely filling the trenches and substantially covering the substrate between the trenches in a contiguous sheet, chemical mechanically polishing the layer of the first electrically conductive material to an end point where the layer of the first electrically conductive material is substantially reduced in thickness but still forms the contiguous sheet between the trenches, applying a photoresist layer over the layer of the first electrically conductive material to define openings, electroplating a second electrically conductive material into the openings, electroplating a third electrically conductive material in the openings, and removing the layer of the first electrically conductive material in the contiguous sheet between the trenches to isolate the first electrically conductive material in the trenches.
17. The method of claim 16 , wherein the first electrically conductive material comprises copper.
18. The method of claim 16 , further comprising the steps of: depositing a layer of electrically nonconductive material over the substrate, and etching the layer of electrically nonconductive material to expose the third electrically conductive material overlying the trenches.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
September 7, 2001
March 16, 2004
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